Inductive device



March 5, 1957 P. A. VANCE INDUCTIVE DEVICE Filed June 7, 1954 w llall-IN VEN TOR. /77's AttbF/Yey.

United States Patent INDUCTIVE DEVICE Paul A. Vance, Fort Wayne, Ind.,assignor to General Electric Company, a corporation of New YorkApplication June 7, 1954, Serial No. 434,757 7 Claims. (Cl. 336-400)This invention relates to inductive devices such as transformers, andmore particularly to means for re ducing the noise thereof when they arein operation.

A particularly undesirable feature in most transformers and reactors isthe noise emanating therefrom when they are in operation. When a body,such as the core of a transformer or reactor is magnetized there occursa phenomenon known as magnet-ostriction, which is the change indimensions that occurs when a body is magnetized. This results in aslight increase in the length of the body '(where it is arrangedlengthwise to the lines of flux), and an even slight'er decrease in thewidth thereof.

Transformers and reactors are most commonly used in connection with 60cycle alternating current. Because of the phenomenon ofmagnetostriction, the use of such current for a transformer or reactormeans that the core elements will change their lengths 120 times persecond. This causes an undesirable vibratory hum, which, in the past,has been amplified considerably by magnetic or mechanical excitation ofother parts of the device, such as coils, casings, covers, and the like,in response to the vibrations of the magnetic structure. Lln addition tothis, it will be apparent that the individual elements of the core willrarely, if ever, be perfectly parallel, with the result that small gapswill be created between them at some points while they are in closecontact with each other at other points. The stresses caused bymagnetization will cause each core element to tend to move as it ismagnetized thereby changing the spacing between the elements Where theyhad occurred and making the elements move with the result thatadditional noise is created. It will be apparent that there is no way toprevent the phenomenon itself, that is, the core cannot be preventedfrom changing in dimensions in response to the cycling change inmagnetic flux. Nor would it be practical to avoid the second cause ofnoise by making the individual elements perfectly parallel, since thiswould result in an extremely expensive device. One solution to theproblem therefore lies in sufliciently isolating the core from the coilor coils so that the vibrations will not be transmitted thereto, and insufficiently isolating that part of the core which expands and contractsfrom the casing means so that the casing will not amplify the sound butwill, as it should, dampen it. 7

It is, therefore, an object of this invention to provide an improvedinductive device which will provide the desirable features set forthabove.

Further objects and advantages of this invention will become apparentand the invention will be better understood by reference to thefollowing description and the accompanying drawing, and the features ofnovelty which characterize this invention will be pointed out withparticularity in the claims annexed to and forming a part of thisinvention.

This invention, in its broadest aspect, provides an in ductive devicehaving a magnetic core with a coil positioned on a leg thereof. Meansare provided, preferably 2,784,384 Patented Mar. 5, 1957 at the ends ofthe coil, so that it is securely clamped into position independently ofthe core. It is of course, preferable that the means at the top of thecoil be spaced from the core so that the vibrations therefrom will notbe transmitted to the coil. Additional means may be provided to securethe clamping means to a casing. The core may be secured between thebottom of the clamping means and the casing member so that the change involume and the resulting vibration will occur at the top of the core,which is spaced from the other elements, so that the vibrations will notbe transmitted to the casing member. It is of course, possible to anchorthe transformer by other means; this may be effected by providingresilient means at all points of connection with either the clampingmeans, the coil, or the cover, so that rather than depending upon theclamping of the core to prevent vibrations at any point, the vibrationsare permitted but effectively dampened before they reach the rest of theelements.

In the drawing:

Figure 1 is a front view of a transformer provided with the improvednoise reducing means of this invention;

Figure 2 is a side view of the apparatus of Figure 1;

Figure 3 is a view in perspective of the apparatus of Figures 1 and 2;and

*Figure 4 is a cross section through line 4-4 in Figure 1.

Referring now to the figures of the drawing, there is shown a core typetransformer, generally identified as '1. It will be understood that thistype of transformer is used for purposes of illustration and that anyother type of inductive device may be used in connection with theinvention with equal effectiveness. The core of transformer 1 has a pairof legs 2 and 3 which are mechanically and magnetically connectedtogether by a top yoke 4 and a bottom yoke 5. These parts of thetransformer core are generally made up of groups of relatively thinlaminations of magnetic material. It will, however, be understood thatthe problem of magnetostrictive noise is not limited to cores of thistype, and that this invention is applicable to any magnetic corestructure (such as wound cores, for instance) in addition to that setforth above for illustrative purposes. Strengthening clamps 6 and 7 maybe provided along the top yoke 4 of the transformer. Clamps 6 and 7 willgenerally be provided on each side respectively of yoke 4 and securedtogether by means of bolts or rivets 9. A pair of coils 10 and "11 arepositioned on legs 2 and 3 respectively. These coils are generally madeup of suitable copper or aluminum conductors. It will be understood thatsuitable electrical connections to the coils 10 and 11 are provided;however, these form no part of the present invention and therefore havebeen omitted for greater clarity. Each of the coils 10 and 11 willgenerally be provided with an inside insulating sleeve 12 and,frequently, with an outside insulating cover 13.

In order to mount the core and coils, there are provided a pair ofclamping members 14 and 15 positioned respectively on opposite sides ofthe core legs 2 and 3, preferably parallel to each other, and to thesides of the core legs, and extending entirely across and beyond thecoils 10 and 11. Members 14 and 15 are secured to two pairs of members16 and 17 respectively, and to each other as by bolts 18 and nuts 19.Spacers 20 are provided respectively for bolts 18 and are positionedaround the bolts so as to maintain a definite clearance between thesides of the core legs 2 and 3 on the one hand and members 14 and 15 onthe other hand. Members 16 and 17 extend down on each side of thetransformer assembly, and each pair of these members is secured to oneend of a pair of members 21 and 22, as by means of a pair of bolts 23and nuts 24 respectively. No spacer is provided in this instance, andbolts 23 are used to clamp securely members 21 and 22 to the sides ofthe bottom core yoke 5. It will be observed that members 21 and 22arepreferably formed as L-shaped members, member 23. comprising legs 25and 26 and member 22 comprising legs 27 and 28, and that members 21 and22 are preferably substantially parallel to members 14 and 15, andcoextensive therewith. Members 16 and 117 secure top members 14 and 15to bottom members 21 and 22 respectively, so that coils 10 and 11 aresecurely clamped between the top and bottom members. Also, by arrangingmembers 14 and 15 outside members 16 and 17 respectively, all contact ofthe top members with the transformer core is avoided. The arrangement ofmembers 14, 15, 21, and 22 is such that coils 10 and 11 are clampedindependently of the core and out of contact therewith.

While the clamping means just described will generally be sufficient tomaintain coils 10 and 11 entirely separate and isolated from the corelegs 2 and 3 respectively, it may be desirable to insert flexiblespacers which may, for instance, be made of a relatively soft grade ofrubber and arranged between each core leg and the coil positionedthereon substantially parallel to members 16 and 17. Spacers of thistype, such as 29, will not transfer the vibration of the core leg to thecoil, but will insure that the coil is kept at a minimum distance on allsides from the core.

It will be seen that the transformer core is tightly clamped at thebottom and that this is effected by placing members 21 and 22 withinmembers 16 and 17 respectively, whereas the spacing from the core at thetop was achieved by placing members 14 and 15 outside members 16 and 17respectively. By this arrangement, unnecessary strain from bending isavoided as to the various members. In order to secure properly theassembly to some secure base, such as an outer cover 31, a pair of boltopenings 30 may be provided in legs 26 and 28 of members 21 and 22respectively. Legs 26 and 2% are preferably arranged to lie in the sameplane when assembled. Thus, the assembly may be secured, as is best seenin Figure 2, to rigid outer cover 31 by means of bolts 32 extendingthrough openings 30. It will be understood that any other appropriatemeans of holding the assembly to the outer cover may be used with equaleffectiveness, either by rigid or flexible connections.

It will be observed that there has been provided means by which thebottom of the transformer core may be securely clamped so that the majorpart of the vibrations, which must inevitably occur, will come about atthe top part of the core. It will further be seen that the assembly ofthis invention permits the top part of the core to be completelyseparated from the coil so that the vibrations will not be transmittedthereto. In addition, the apparatus is so designed that it may besecured to an outer covering at any location where the vibrations areminimized so that the outer covering will dampen the noise from thevibrations because of its relative isolation from the vibrating part ofthe device.

While this invention has been explained by describing a particularembodiment thereof, it will be apparent that improvements andmodifications may be made without departing from the scope of theinvention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. Noise-reducing means for inductive device having a substantiallyclosed laminated core with a coil positioned on a leg thereof, saidmeans comprising a member engaging the one end of said coil on a side ofsaid core, said member being spaced from said core, a second memberengaging the other end of said coil on a side of said core, meansconnecting said members thereby to clamp said coil therebetween, saidcoil being maintained on said leg out of contact therewith and.independently thereof by said clamping means, said second member beingclamped to said core, said connecting means and said coil both beingspaced from said core at said one end of said coil whereby said noisereducing means and said coil are both entirely out of contact with saidcore at said one end of said coil.

2. Noise-reducing means for an inductive device having a substantiallyclosed laminated core with a coil positioned on a leg thereof, saidmeans comprising a pair of members engaging one end of said coil on eachside of said core respectively, said pair of members being spaced fromsaid core, a second pair of members engaging the other end of said coilon each side of said core, and means connecting said pair of membersthereby to clamp said coil therebetween, said coil being maintained onsaid log out of contact therewith and independently thereof by saidclamping means, said second pair of members being further arranged toclamp tightly against each side respectively of said core, saidconnecting means and said coil both being spaced from said core at saidone end of said coil whereby said noise reducing means and said coil areboth entirely out of contact With said core at said one end of saidcoil.

3. Noise-reducing means for an inductive device having a substantiallyclosed laminated core with a coil positioned on a leg thereof, saidmeans comprising a pair of relatively long and thin members engaging oneend of said coil on each side of said core respectively and being spacedtherefrom, said members extending substantially parallel to each otherand to the sides of said core, a second pair of relatively long L-shapedmembers engaging the other end of said coil on each side of said corerespectively and each having one leg tightly engaging a side of saidcore, said second pair of members extending substantially parallel tosaid first pair of members, all of said members having their endsextending beyond said core and said coil, third and fourth pairs ofelongated members, each of said third pair having its ends securelyfastened to an end of one of said first pair and an end of one of saidsecond pair respectively, each of said fourth pair having its endssecurely fastened to the other end of one of said first pair and theother end of one of said second pair respectively thereby to clamp saidcoil on said leg out of contact therewith and independently thereofbetween said first and second pairs, the other legs of said second pairlying in a plane and being adapted to be secured to a base, said thirdand fourth pairs and said coil all being spaced from said core at saidone end of said coil whereby said noise reducing means and said coil arebothentirely out of contact with said core at said one end of said coil.

4. Noise reducing means for an inductive device having a substantiallyclosed laminated core with a coil positioned on a leg thereof, saidmeans comprising a pair of relatively long and thin members engaging oneend of said coil on each side of said core respectively and being spacedtherefrom, said members extending substantially parallel to each otherand to the sides of said core, a second pair of relatively long L-shapedmembers engaging the other end of said coil on each side of said corerespectively and each having one leg tightly engaging a side of saidcore, said second pair of members extending substantially parallel tosaid first pair of members, all of said members having their endsextending beyond said core and said coil, third and fourth pairs ofelongated members, each of said third pair connecting respectively anend of said first pair and an end of said second pair, each of saidfourth'pair connecting respectively another end of said first pair andanother end of said second pair thereby to clamp said coil between saidfirst and second pairs of members, the other legs of said second pairlying in a plane and being adapted to be secured to a base, and aplurality of resilient spacer members extending between said coil andsaid core thereby correctly to position said coil on said cone forclamping, said third and fourth pairs and said coil all being spacedfrom said core at said one end of said coil whereby said noise reducingmeans and said coil are both entirely out of contact with said core atsaid one end of said coil.

5. In combination, an inductive device comprising a substantially closedlaminated core having a leg with a coil positioned on said core leg; andnoise-reducing means comprising a pair of members engaging one end ofsaid coil on each side of said core respectively, said pair of membersbeing spaced from said core, a second pair of members engaging the otherend of said coil on each side of said core, said second pair of membersbeing secured to said core, means connecting said pairs of membersthereby to clamp said coil therebetween, and resilient spacerspositioned between said core and said coil to ensure separation thereofwhen said coil is so clamped, said connecting means and said coil bothbeing spaced from said core at said one end of said coil whereby saidnoise reducing means and said coil are both entirely out of contact withsaid core at said one end of said coil.

6. In combination, an inductive device comprising a substantially closedlaminated core having a leg with a coil positioned on said core leg; andnoise-reducing means comprising a pair of relatively long and thinmembers engaging one end of said coil on each side of said corerespectively and being spaced therefrom, said members extendingsubstantially parallel to each other and to the sides of said core, asecond pair of relatively long L-shaped members engaging the other endof said coil on each side of said core respectively and each having oneleg tightly engaging a side of said core, said second pair of membersextending substantially parallel to said first pair of members, all ofsaid members having their ends extending beyond said core and said coil,third and fourth pairs of elongated members, each of said third pairhaving its ends securely fastened to an end of one of said first pairand an end of one of said second pair respectively, each of said fourthpair having its ends securely fastened to the other end of one of saidfirst pair and the other end of one of said second pair respectivelythereby to clamp said coil between said first and second pairs, theother legs of said second pair lying in a plane and adapted to besecured to a base, and a plurality of elongated resilient spacersarranged about said leg Within said coil substantially parallel to saidleg, said third and fourth pairs and said coil all being spaced fromsaid core at said one end of said coil whereby said noise reducing meansand said coil are both entirely out of contact with said core at saidone end of said coil.

7. In combination, an inductive device comprising a substantially closedlaminated core having a pair of parallel legs and a pair of yokesjoining said legs at their ends with a pair of coils mountedrespectively on said legs; and noise-reducing means comprising a pair ofrelatively long and thin members engaging one end of said coils on eachside of said core respectively, said pair of members being spaced fromsaid core, said members extending substantially parallel to each otherand to the sides of said core, a second pair of relatively long L-shapedmembers engaging the other end of said coils on each side of said corerespectively and each having one leg tightly engaging a side of saidcore, said second pair of members extending substantially parallel tosaid first pair, all of said members having their ends extending beyondsaid core and said coils, third and fourth pairs of elongated members,each of said third pair connecting respectively an end of said firstpair and an end of said second pair, each of said fourth pair connectingrespectively another end of said first pair and another end of saidsecond pair whereby said coil is clamped between said first and secondpairs of members, the other legs of said second pair lying in a planeand adapted to be secured to a base, and a plurality of resilient spacermembers extending between said coil and said core substantially parallelto said third and fourth pairs thereby correctly to position said coilon said core for clamping, said third and fourth pairs and said coil allbeing spaced from said core at said one end of said coil whereby saidnoise reducing means and said coil are both entirely out of contact withsaid core at said one end of said coil.

References Cited in the file of this patent UNITED STATES PATENTS1,304,257 Brand May 20, 1919 1,382,873 Wagner June 28, 1921 1,536,761Brand May 5, 1925 FOREIGN PATENTS 173,800 Great Britain Jan. 16, 1922891,942 France Mar. 23, 1944 605,138 Great Britain July 16, 1948

